In yesterday's discussion of a Cuevas bike David White pointed to his wooljersey gallery, and there his comment drew my attention to, quote: "the very sweet fluted seat stay caps that twist over the top tube."
Here's a very nice looking frame with a similar (to my eye) seatstays treatment (not mine, no relation to seller etc):
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Cheers,
Dmitry Yaitskov,
Toronto, Canada.